1. a form of compulsion involving a rigid or stereotyped act that is carried out repeatedly and is based on idiosyncratic rules that do not have a rational basis (e.g., having to perform a task in a certain way). Rituals may be performed to reduce distress and anxiety caused by an obsession.

2. a ceremonial act or rite, usually involving a fixed order of actions or gestures and the saying of certain prescribed words. Anthropologists distinguish between several major categories of ritual, although these can often overlap in practice: magic rituals, which involve an attempt to manipulate natural forces through symbolic, often imitative, actions (e.g., pouring water on the ground to make rain); calendrical rituals, which mark the changing of the seasons and the passing of time; liturgical rituals, which involve the reenactment of a sacred story or myth, as in the Christian eucharist and many other religious rituals; rites of passage; and formal procedures that have the effect of emphasizing both the importance and the impersonal quality of certain social behaviors, as in a court of law.

3. more generally, any habit or custom that is performed routinely and with little or no thought. —ritualism n. —ritualistic adj.